The maximum length of time you can wear the drainage tube for rectal cancer surgery cannot be generalized, it needs to be combined with the amount of drainage flow and the color of drainage fluid. It is generally believed that the drain can be removed 3~5 days after rectal cancer surgery. The drain can be left in place after surgery to discharge the drainage fluid for wound healing, and at the same time, the recovery of the wound can also be judged by the drainage situation. If the postoperative drainage is bright red, or the drainage flow is large, more than 150 ml per day, then we need to consider that there is more bleeding, then we should not rush to remove the drain, and we need to closely observe the drainage situation, and if necessary, review the blood routine, in order to decide whether to take non-surgical treatments, such as transfusion, hemostasis, and so on. If the postoperative drainage fluid is light red and the amount of drainage is less than 50~100 ml per day, it indicates that less fluid is generated and less bleeding, then the removal of the drainage tube can be considered. Therefore, the maximum length of time a drain can be worn after surgery needs to be judged in relation to the color and volume of the drainage fluid.